The present invention relates to a broadcasting unit for broadcasting in an access network channels of a distributive interactive service to a plurality of user terminals and an access network including such broadcasting units.
Such a broadcasting unit and access network are already known in the art, e.g. from the U.S. Pat. No. 5,557,316, entitled ‘System for Distributing Broadcast Television Services Identically on a First Bandwidth Portion of a Plurality of Express Trunks and Interactive Services Over a Second Bandwidth Portion of Each Express Trunk on a Subscriber Demand Basis’. Therein, an interactive television information system is described wherein each broadcasting unit, named headend in the cited US Patent, broadcasts fixed television channels via a first bandwidth portion and broadcasts selected television channels in response to subscriber requests via a second bandwidth portion. The television channels selected in response to subscriber requests and broadcasted via the second bandwidth portion are selected amongst all television channels supplied to an input of the headend or broadcasting unit. A drawback of the known interactive television information system is that all television channels have to be supplied to inputs of all broadcasting units in the access network. Even if none of the subscribers served by a broadcasting unit request a certain television channel, this channel will be available at the input of this broadcasting unit. Consequently, a significant amount of the transfer capacity of the links in the known access network is inefficiently used to transfer television channel information that is not requested by the subscribers to the broadcasting units that serve these subscribers.